Maddison, 20, has been impressive in the Championship this season and starred against Arsenal in the Carabao Cup fourth round.
Everton's interest should act as a wake up call to Tottenham, who blew the chance to sign Maddison in 2016.
Tottenham were considering a Dele Alli type deal which would have involved buying him for £5 million and loaning him back to the Sky Blues.
It came a surprise when days later they were beaten to his signature by Norwich, whose acquisition is starting to bear fruit.
If Maddison is up for grabs at the right price this January then Tottenham will be able to redress their past error, but it could be their final opportunity to do so if Everton win the race.
Signing Maddison would allow Tottenham to somewhat make up for their previous errors, and if it helps swing the deal they should consider loaning him back to Norwich until the end of the current campaign.